Weight-controlled air valve for carburetors



C. H. KIRBY March 31 1931.

WEIGHT CONTROLLED AIR VALVE FOR GARBURETORS 7 Filed Dec. 12, 1927 I5 Sheets-Sheet l c.' H. KIRBY March 31, 1931.

WEIGHT CONTROLLED AIR VALVE FOR CARBURETORS Filed Dec. 12, 1927 3 Sheets-Sheet 2 a V//IIIIIIIIIIII/ m m ///j/jrl wllfi/l/llldv/l KIRBY 1,798,161

12, 1927 '5 Sheets-Sheet 5 March 31, 1931. c. H.

WEIGHT CONTROLLED AIR VALVE FOR CARBURETORS Filed Dec.

Fetentesl Marc 35% @331 metres srares earner orrice CHARLES E. KERRY, F FLINT, MICHIGAN, ASSIGNQH T0 MARVEL CABIBU'RETER COM- PANY, OF FLINT, MICHIGAN A CORPORATICN OF ILLINOIS WEIG-HT-CQBTTEOLLED AIR VALVE EOE CARBUEETOR$ Application. filed December 12 1927. Serial Ito. 239,875.

This invention relates to a carburetor for internal combustion engines and has special reference to a new type of weighted or gravity actuated auxiliary air valve.

It is an object of this invention to provide a carburetor of the class described wherein a primary air supply is through an adjustable but constant area passage, this air supply acting to pick up all the fuel required by the engine; the resulting very rich mixture being diluted by varying volumes of air automatically proportioned to the suction in the carburetor by means of a gravity or weigh-ted type of air valve.

It is also an object of this invention to provide means to regulate the responsiveness of the weighted air valve to the suction of the carburetor by in eii'ect varying the weight of the valve by regulat-.

ing the eilective suction acting over the major area of the valve. This result is accomplished by incorporating a loosely filling dash pot and piston in the valve structure in order that the suction in the carburetor will be communicated to the interior of the dash pot and in providing a regulatable air bleed into the dash ,pot whereby the efi'ectiveness of the carburetor suction within the dash pot can be manually controlled.

Other and further important objects of this invention will be apparent from the disclosures in the drawings and specification.

This invention (in a preferred form) is illustrated in the drawings and hereinafter more fully described.

On the drawings:

Figure 1 is a central vertical section of a carburetor embodying the features of this iii-- 0 vention, the throttle valve in this figure being nearly closed.

Figure 2 is a fragmentary section similar to Figure 1 wherein the throttle valve is half open. p

Figure 3 is another similar section show ing the relationship of the parts when the throttle is fully open.

Figure 4 is a fragmentary section of a slightly modified iorm.

Figure 5 is a section on the line V-V of Figure 4-. 4

As shown on the-drawings:

The carburetor chosen to illustrate the application of this invention comprises a horizontal Venturi casing 10 having the usual throttle valve ll-mounted therein, a chamber 12 being formed in a casing 13 below and integral with the Venturi casing. A cover 14 for the casing 13 serves as a mounting for an air bleed type of fuel nozzle 15 and for an electric heating element 16 having an insulated terminal 17 projecting through the cover, this particular structure being espe cially advantageous as removing the cover also removes the nozzle and heating element intact as a unit. The cover 14 is apertured for a fuel. inlet 18 and an outlet 19 communicating with the nozzle 15, a needle valve 20 being mounted in the cover 14 in alignment with the outlet passage 19 to control the flow of fuel theretnrough. A nipple 21 screwed into the inlet 18 serves to mount the usual form of float chamber 22 having a float 23 operating a float valve 24 which controls the admission of fuel through a screened inlet passage 25. The fuel nozzle 15 discharges into a passaged plug 26, the passage of which is tapered to a restricted diameter tube 27 which extends upwardly into the Venturi passage approximately at the throat or point of greatest restriction thereof. The chamber 12 is supplied with a limited quantity of air which may he heated by the heating element 16 it a; desired; this air being drawn up through the plug 26 by the Venturi suction and in turn having a strong ejector efi'ect on the fuel nozzle 15, initially forming a very rich fuel and air mixture which is diluted to the ing through the Venturi.

The rear portion of the Venturi casing 10 is formed as an open vertical cylinder 28 having an air valve seat 29 at the bottom and a threaded opening 30 therebelow to receive an adjustable air nozzle 31, the space 32 between the nozzle 31 and the walls of the opening 30 forming a primary air supply passage feeding through a port 33 to the interior of the casing 13. By adjusting the air nozzle up or down in the threaded opening, the space between the tip of the nozzle and the lower face of the valve seat can be varied to vary the supply of primary air to the fuel nozzle chamber in the casing 13.

A cap 34 forms a top closure for the cylindrical rear portion of the Venturi casing 10, this cap having a downwardly projecting apertured boss 35 concentric with the a is of the air valve seat, this boss serving as a pilot for the stem 36 of a weighted or gravity type of air valve 37 which normally rests on and seals the valve seat 29 without altering the primary air supply to the port 33. The weighted or gravity type of air valve presents a constant resistance to movement by the air pressure acting thereon due to suction in the Venturi casing, so that a substantially constant pressure differential is required to lift the valve whether it is closed or already partially open. \Vith a spring pressed air valve the pressure difference must increase in proportion to the compression of the spring,

1 thus disturbing the balance between the air supplied through the valve and the suction in the Venturi casing. lVith the weighted valve the balance is constant, thus supplying the large additional amount of air required at full throttle opening with only a slight increase in the suction .in the Venturi casing, the extra supply of air reacting to reduce the extreme. suction and to thereby increase the volumetric etliciency of the engine.

The cap 34 carries a depending cylindrical shell 38 which envelops an upstanding vlindrical shell 39 on the air valve 37 there. being a limited clearance between the two shells to permit escape of air from the space 40 enclosed by said shells. This space 40 is supplied with a regulated quantity of air through a nipple-41' and pipe 42 leading to a control valve body 43 which may be mounted on the control panel 44 of a vehicle. A cap having a needle valve 46, is screwed onto the body 43. the valve 46 entering the air passage 47 through the body to regulate or shut off the flow of air therethrough. In order to limit the maximum adjustment the air is admitted to the inside of the cap through apertures 48 in the body43 and a snap ring 49 is positioned in the cap to hunt the outward movement thereof. The air supplied to the space 40 is used to regulate the responsiveness and movement of the weighted weight of the valve 37 and correspondingly retarding its opening movement.

It will be evident from the foregoing description that the operation of the carburetor is as follows. The primary air supply throughthe heating element to the fuel noz zle is through a passage of constant area S(. that the volume of air flow will be a function of the suction'at the outlet of the injector plug nozzle. The fuel picked up 'due to the injector effect will also vary as a function of the suction created. The fuel and air mixture thus formed will be increasingly rich with increases in the Venturi suction so that the required additional air is supplied through the weighted air valve, the operation and regulation of which has been previously described.

In the modification shown in Figures 4 and 5 a manifold connection 50 is shown embodying the throttle valve and an exhaust heated jacket 51-, a Venturi 52 being mounted in the passage 53 below the throttle. A carburetor body 54 is' bolted to the manifold connection and is formed with an air passage 55 leading from an air valve seat 56, corresponding to the seat 28, to the passage 53. An injector tube 57 extends upwardly into the passage 55 in alignment with the venturi 52, a fuel nozzle 58 of the air bleed type being mounted in a primary air chamber 59 and supplied with fuel through a passage 60 from a float chamber 61 indicated in outline in the background of Figure 4. The fuel passage 60 is adjustably cut off from the fuel nozzle by a needle valve 63 seating in a renewable passaged plug 64 which is screwcdinto the fuel nozzle 58.

In this modification an air inlet nozzle 65 corresponding to the nozzle 31 is fixed in spaced relationship to the air valve seat 56, the primary air supply to the air chamber 59 being through a passage 66 controlled by a needle valve 67 and thence through a port 68 to the chamber 59. The needle valve 67 performs the same function as the adjustable nozzle 28 previously described in connection with the form shown in Figures 1 and 4.

A cap 69 is mounted in the body 54 concentric with the air valve seat 56 and a dash pot chamber 70 is formed therein about a hollow pilot 71 within the sleeve-like stem 72 of a weighted air valve 73 which has a piston 74 loosely fitting in the dash pot to permit escape of air between the piston and the cap walls. A check valve permits ready inflow of air into the dash pot from the carburetor body but limits the escape of air to leakage past the piston so that the dash pot is effective as a check on the upward movement of the air valve 73. The chamber 76 within the stem 72 and pilot 7 3 is utilized as a further check acting in both directionsby providing a restricted areapassaged plug 77 therefor. The dash pot chamber 70 is supplied with a regulatable quantity of air through a regulating device such as has'been previously described in connection with Figure 1, the eflect of the air supply to the dash pot being the same as heretofore described.

It will thus be seen that I have produced an improved and simplified carburetor wherein a weighted type of air valve is responsive to suction in the carburetor and the responsiveness thereof can be adjusted to regulate the mixture ratio to secure the best performan ce under the varying conditions of service. Such a weigh'ted or gravity actuated valve will open farther with less pressure differential than is possible wit-h a spring urged valve because the spring pressure builds up as the valve opens, so that the weighted valve results in a higher volumetric efiiciency at maximum speeds and loads, correspondingly increasing the maximum power from a given engine.

I am aware that many changes. maybemade and numerous details of construction may be varied through a wide range without departing from the principles of this invention and I, therefore, do not purpose limiting the patent granted hereon otherwise than necessitated by the prior art.

I claim as my invention:

1. In a carburetor of the class described, a Venturi air passage having a valve seat at its inlet, a weighted air valve in cooperating relation to said valve seat, a dash pot associated with said valve, and a primary air passage bypassed around said air valve and uninfluenced by the position of said valve.

2. In a carburetor of the class described, a Venturi air passage having a valve seat at its inlet, a weighted air valve in cooperating re? lation to said valve seat, a dash pot associated with said valve, a primary air passage bypassed around said air valve, and means for independently regulating the area of said bypass passage.

3. In a carburetor of the class described, a Venturi air passage having a valve seat at its inlet, a weighted air valve in cooperating relation to said valve seat, a dash pot associated with said valve, a primary air passage bypassed around said air valve and independently thereof, and an electric heating element in said bypass passage.

4. In a carburetor of the class described, a Vcnturi air passage having a valve seat at its inlet, a Weighted air valve in cooperating re lation to said valve seat, a dash pot associated with said valve, a primary air passage independent of said air valve, means for regulating the area of said passage independently of said air valve, and an electric heating element in said bypass passage.

5. In a carburetor of the class described, a Venturiair passage having a valve seat at its inlet, a Weighted air valve in cooperating relation to said valve seat, a dash pot associated with said valve, and an adjustable air bleed into said dash pot.

6. A carburetor of the class described comprising a primary air supply passage, 2. fuel nozzle therein, a main air passage of the Venturi type into which the primary fuel and air supply discharges at the throat of said venturi, a valve seat forming the air inlet to said venturi, a weighted air valve cooperating with said seat, a dash pot cylinder, a piston loosely fitting therein and forming part of said air valve, and means for admitting a regulated flow of air into the space inclosed by said cylinder and piston, said loosely tittedpiston beingadapted to permit air leakage into the venturi.

7. A carburetor of the class described comprising a primary air supply passage, means for regulating the volume of flow through said passage, a fuel nozzle therein, a main air passage of the Venturi type into which the primary fuel and air supply dischargesat the throat of said venturi, avalve seat forming the air inlet to said venturi, a weighted air valve cooperating with said seat, a dash pot cylinder, :1 piston loosely fitting therein and forming part of said air valve, and means for admitting a regulated flow of air into the space inclosed by said cylinder and piston, said loosely fitted piston being adapted to permit air leakage into the venturi.

7. A carburetor of the class described comcomprising a primary air supply passage, air heating means in said passage,a fuel nozzle therein, a main air passage of the Venturi type into which the primary fuel and air supply discharges at the throat of said venturi, a valve seat forming the air inlet to said venturi, a weighted air valve cooperating with said seat, a dash pot cylinder, a piston loosely fitting therein and forming part of said air valve, and means for admitting a regulated flow of air into the space inclosed by said cylinder and piston, said loosely fitted pis- .ton being adapted to permit air leakage into the venturi.

9. A carburetor of the class described comprising a primary air supply passage, means for regulating the volume of flow through said passage, air heating means in said passage, a fuel nozzle therein, a main air passage of the Venturi type into which the primary fuel and air supply discharges at the throat of said venturi, a valve seat forming the air inlet to said venturi, a weighted air valve cooperating with said seat, a dash pot cylinder, a piston loosely fitting therein and forming part of said air valve, and means for admitting a regulated flow of air into the space inclosed by said cylinder and piston, said loosely fitted piston being adapted to permit air leakage into the venturi.

In testimony whereof, I have hereunto subscribed my name at'Flint, Genesee County,

Michigan.

. CHARLES H. KIRBY. 

